US4468100AExpiredUtilityPatentIndex 74
Wide-angle photographic lens
Est. expiryOct 9, 2001(expired)· nominal 20-yr term from priority
G02B 9/64
74
PatentIndex Score
18
Cited by
6
References
3
Claims
Abstract
A small-size and high-performance wide-angle photographic lens system of the seven-group-seven-element type including first and second components of negative meniscus lenses with convex surfaces directed to the object, a third component of a positive lens having a large-curvature convex surface directed to the object, a fourth component of a positive lens having a large-curvature convex surface directed to the image, a fifth component of a biconcave negative lens, a sixth component of a positive meniscus lens having a convex surface directed to the image, and a seventh component of a positive lens.
Claims
exact text as granted — not AI-modifiedWhat is claimed is:
1. A small-size and high-performance wide-angle photographic lens system having seven lens elements grouped into seven lens components, including first and second components each consisting of negative meniscus lenses with convex surfaces directed to the object, a third component consisting of a positive lens having a large-curvature convex surface directed to the object, a fourth component consisting of a positive lens having a large-curvature convex surface directed to the image, a fifth component consisting of a biconcave negative lens, a sixth component consisting of a positive meniscus lens having a convex surface directed to the image, and a seventh component consisting of a positive lens, said lens system satisfying the following conditions: ##EQU2## where f is the focal length of the overall lens system, f I ·II is the resultant focal length of the first and second components, f I is the focal length of the first component, d i is the thickness or spacing of the i-th lens, N I , N II are the refractive indexes of the first and second components at d-line, f I-IV is the resultant focal length of the first through fourth components, f III ·IV is the resultant focal length of the third and fourth components, f III is the focal length of the third component, and r i is the radius of curvature of the i-th lens surface.
2. The lens system claimed in claim 1, further satisfying the following chart: ______________________________________
aperture ratio
1:2.8 f = 28.78 ω = 37.6° f.sub.B = 36.79
______________________________________
No. r d N ν
______________________________________
1 38.000 1.40 1.58913
61.0
L.sub.1
2 16.614 6.46
3 34.000 1.30 1.51633
64.1
L.sub.2
4 14.850 7.17
5 25.674 4.50 1.70000
48.1
L.sub.3
6 -151.327 4.62
7 94.860 4.75 1.65844
50.9
L.sub.4
8 -28.090 4.00
9 -17.929 3.33 1.76182
26.6
L.sub.5
10 48.280 1.19
11 -33.552 2.40 1.69350
53.2
L.sub.6
12 -16.160 0.10
13 -1141.732 2.50 1.69350
53.2
L.sub.7
14 -30.500
______________________________________
##STR17##
##STR18##
##STR19##
##STR20##
##STR21##
##STR22##
##STR23##
##STR24##
______________________________________
3. The lens system claimed in claim 1, further satisfying the following chart: ______________________________________
aperture ratio
1:2.8 f = 28.63 ω = 37.6° f.sub.B = 36.80
______________________________________
No. r d N ν
______________________________________
1 30.000 1.52 1.58913
61.0
L.sub.1
2 17.006 4.53
3 32.000 1.40 1.51633
64.1
L.sub.2
4 14.000 8.55
5 29.920 3.83 1.74400
44.7
L.sub.3
6 -103.398 4.36
7 -460.000 4.40 1.74400
44.7
L.sub.4
8 -27.625 3.66
9 -18.660 3.66 1.80518
25.4
L.sub.5
10 56.177 1.73
11 -42.690 2.40 1.69680
55.5
L.sub.6
12 -16.750 0.10
13 -487.370 2.50 1.69350
53.2
L.sub.7
14 -30.186
______________________________________
##STR25##
##STR26##
##STR27##
##STR28##
##STR29##
##STR30##
##STR31##
##STR32##
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